Wireless receiving apparatus



July 1,1930. A. H. MACKLEY ET AL 1,769,443

WIRELESS RECEIVING APPARATUS- Filed Nov. 1 1924 Patented July 1, 1930UNITED era-as t ier" ALFRED HENRY MACKLEY, OF IBEDFORD, AND WILLIAM:STANLEY FLIGHT, OF

EALING, LONDON,.ENGLAND 7 'wrnnrlnss nnonrvnve APPARATUS Applicationfiled November 1, 192 4,Seria1 No. 747,155, and in Great BritainNovember7, 1923.

This invention relates to wireless apparatus and has for its object theprovision of means whereby the usual batteries for energizing the valvefilaments may be dispensed with.

Other objects and advantages will appear hereinafter.

The invention may be said to reside essentially in the arrangement, in awireless receiving apparatus including one or more valves, according towhich the filament or filamentsof the said valve or valvesis or areadapted to beenergized from ordinary alternating-current mains throughthe medium of a step down transformer.

Thisstep down transformer may be capable of receiving primary currentsof widely varying potentials and transforming the primary currents intocurrents of difierent lower potentials by widely differing ratios sothat it can be used with a variety of'mains and will supply a varietyof'tilaments; and to this end the transformer may comprise primarywindings and secondary windings adapted to be selectively connectedeither in parallel or in series relation.

Preferably the transformer comprises two primary windings and twosecondary windlugs and switch gear is provided such that the two primarywindings may be connected in series while their corresponding secondarywindin s are in parallel, or such primary windings may be connected inparallel while the secondary windings are in series, or such 85 primarywindings and secondary windings may both be connected in series or mayboth be connected in parallel.

The invention further contemplates the arrangement according to whichthe filaments are connected across the output terminals of thetransformer in parallel with a potentiometer or potentiometerssubstantially as hereinafter specified. I One embodiment of theinvention as applied to a crystal detector three valve amplifying setof. a well known kind, is illustrated in the accompanying drawings andthe same will now be described it being understood that the particularconstruction and arrange- 5O ment shown are susceptible of variousmodifications without departing from the scope of the appended claims.

In these drawings 1 Figure 1 is a schematicview of the complete set. rFigure 2 is an enlarged view of certain control elements used in saidset.

Figure 8 is a section upon line X'X of Figure 2.

Figure at is a view of a vernier potentiometer included in said set.

Referring first to Figure 1, the filaments of the three valves 1, 2 and3 are adapted to besupplied by means ofa step down transformer atenergized from alternating current lighting mains L L Thistransformermay be of any well known kind or it may be specially constructed so asto be capablefof receiving primary currents of widely varying potentialsandtransforming them into currents at different lower potentials bywidely varying ratios so that it can be used with a variety of-mains"and will supply a variety of filaments. In this latter case the transformer comprises primary windings and secondary windings adapted "to beselectively connected either in parallel or in series relation. v

An example of such atr'ansformer is illustrated in the drawings and willbe described later. For the present it is sufficient to state that theleads 5 and 6 are adaptedto be supplied from the transformer with a'suitable current for lighting the filaments of the three'valves, whichfilaments are connected across these leads 5 and (Sin parallel,rheostats 7 8 and 9. being connected each to each as shown in theindividual circuits of said filaments. The amplifier input circuit isconnected across the grid of the first valvel and the slide of apotentiometer 10 (of say two hundred ohms) connected across the saidleads 5 and 6, a

' negative bias battery-11 of say 3.5 volts being connected in saidcircuit in the position shown. The said first valve 1 is adapted tosupply and control the second valve 2 through the medium of, a radiofrequency transformer unit comprising transformers 12 and 18,'a' crystaldetector 14 and condensers 15' and 16 all arranged, as shown, in accordance with wellknown practice. 'rh outvalve 2 and the'islid'e of asecond potentiom-g :eter 17 (to be more particularly described itpihereinafter) alsogconnected across the leads .5. and 6, a secondnegative bias battery 18 j alsorconnected in this output circuit.

second valve 2is adapted. to supply and conof similar voltage to thebatteryll beli nlg e I trol theth ird valve 3 through the medium 20. rqThefunctionpof the potentiometers isto keep the normal; voltage of thegrids at a of an audi'qifrequency transformer 14? the secondary. orwhich is connected, across the grid of said third valve? and the slideof the aforesaid.potentiometer 17 through the me diumcf the aforesaidbattery 18. g r Obvio'usly however, instead of thecommon' potentiometerV 17 separate potentiometers may desired beconnected in the respectiveinputcircuits of the valves 2and 3.

Steady value with respect to the average voltage of theelectricalmidpoint of the filament and thus minimize the hum which variations of thegrid voltage would otherwise a produce. All the resistancesof thedeviceare In some cases, however, it is not possible, by

adjusted until the hum is reduced to a min- 7 meansfofthesepotentiometers to entirely eliminatehum, owing to the fact that the gridconnection tothe alternating current is through the. secondary of atransformer whereasvthe filament connection to the same alternatingcurrent is direct. This causes the potential ,fiuctuations in the gridtobe out of phase with those of the filament. ,In' order to remedy such]out of phase fluctuations L between the :grid, and the filament (and, if

.necessary,-the,plate) wemayemploy a choke coil of adifl 'erential typeformed of an, iron ome? on" which are wound two windings48 and 49,;theformer beinggcon'nected in series in; thei g rid lead and the latterbeingconnect.

. ed in. series in the filament lead. These windings are in magneticopposition: and are so proportioned that "when the potentialflucytuations. lIL-thBmyaIfB in-phase there is no fluxein the core; IOut of phasepotential fluc tuationshowever, induce an alternating fluxinjthe core so that the apparatus acts as a" choke tendingto damp outofphase voltages t an nsi y Proportional to h nt 0nd of its two positionsthecontacts b and 0 will be connected by. one of the strips 27, theother strip 27 being ineffective as it only by which they are outof'phase. w

1 Describing nowthe step down transformer 4 and its 'as'sociated partsthe same comprises we primary windings 19'. and 20 and two and 6 in thefollowing manner.

windings are in series, or such primary windings and secondary wlndlgsmay both be arranged i'nttwo sets of six each, the one set consisting ofcontacts a, b, 0,'cZ, e and f and the other-set consisting of contacts a6 0 (Z311 and j. The contacts (1,7), 0, Z, a 6

' 0' (1 L are permanently connected to thefother 1 parts of theapparatus as shownin full lines in Figure .1 and the contacts 6, fie andf are dead. The contacts ofeach set; are arranged symmetrically around acommon cen-' tre and are separated from one another by equal intervals.1 y

' The switch gear also comprises two movable plug members and 26 eachhaving six prongs a 6 0 d 6?, and f disposed-so, as

to be adapted to beplugged respectively into the six socket contacts ofeither set.

7 As the plugs are symmetrically arranged it will be obvious that eitherplug could, by itself, be

plugged intojeitherset of socket contacts in any of slx dlfferentangular positions, but

owing to the fact that thebody portions of the plugs are formed eachwith two flat faces and that the two sets of sockets are so spaced that(the plugs can only be both plugged at the same time when a fiat faceofconnected in series or may both be connected each is in engagementwith a flat face of the other, the plugs are only really capable ofbeing plugged each in either of two positions.

via, the plug 25 in positions in which the prongs c? and f or the prongs(Hand 6 are i vertical (according to the drawing) and the plug 26 in,positions in which the prongs e and f orthe. prongs f ,andc are vertical(according to the drawing); As shown, moreover,- in Figure 2eachplugghas its prongs a and]; and its prongs o and 6Z2 connectedtogether by metal strips 27, the prongs c and f being dead.

Thus, as is clear fromFigure lvwhen the plug 25 is inthe first of itssaid two positions the contacts a and b and the contacts 0 andd will bebridged and electrically connected by the strips 27 and when the sameisin the secserves to connect the contact d to the contact 6 whichis dead.Similarly when the plug ondof its two positions, the contacts b and awill beconnected.

- The'plug 25 is-adapted tocontrol the con-L nections of the primarywindings '19 and 20 and-the plug 26 is adaptedto control the connectionsof the secondary windings 21 and 22 as will now be described.

As will be clearly seen from Figure '1,

when the plug25 is in the first of its two positions in which I) isconnected to aand is connected to (Z the coil 19 willbe' connecteddlrectly across the mains L and L through c and (Z and'the coil 20 willbe connected directly acrosssaid mains through a and b.

When, however, the plug 25 is. in the second i of its two positions inwhich I) is connected to 0 the coils 19 and 20 will be connected acrossthe mains in series with one another;

In exactly the same way, the plug 26, in the first of its two'positionsconnects the coils '21 and 22 in parallel across the leads 5 and 6, and,in the second of its two positions connects said CO1lS 1n series withone another across said leads 5 and 6.

In the particular embodiment described I the primary windings 19 and 20are each adapted to take 120 volts and the secondary windings 21 and 22are each adapted to take 3 volts.

Therefore when the mains which it is 1 required to use are in theneighbourhood of mains are in the neighbourhood of 120 volts.

On the other side when the filaments being used are of about 3 volts thesecondary windings will be connected in parallel across the leads 5 and6, with the-plug 26 111 its first position, whereaswhen they are ofabout 6 voltsthe secondary windings will be connected in series acrossthe leads 5 and 6, with the plug 26 in its second position.

Against each straight face F is inscribed the voltage for which therespective plug is set when the said face is the face which is againstone of the faces on the other plug.

In cases where only one low voltage supply is required, say at six voltsit is obvious that only the plug would be required,the

secondary winding being of ordinary construction. In this case the flatfaces F of the plug could co-operate with a suitable fixed fiat face.

The aforesaid potentiometer 17 is specially designed so as to give thevery fine control which is sometimes found necessary especially inconnection with valves of low frequency. v To this end a rheostatwinding 28 m of say 30 ohms maximum resistance isconnected in serieswith the winding 29 of a potentiometer proper of say 300 ohms resistance(see Figures 1 and 4). Obviously when the closest possible adjustmenthas been made on the slide of the winding 29 the potential at the saidslide may be very much more closely adjusted through adjustmentof theslide of the rheostat winding 28.

"Asshown in Figure-f the windings 28 and" 29 extend aroundtheperipheries of respective insulating drums 301 and 31 which drumsareimounted respectively upon-corn.

centric shafts 32j a nd 33" adapted toqbe independently rotated by,knobs 34 and 35. Each of the drums is provided with flanking side plates36. and 37 of metal and the: drums are mounted respectively in 1116-,tallic-U-shaped brackets .38 and 39 which form bearings for the shafts32 and 33 as; shown. Thesaid brackets are secured andelectricallyconnected together and the bracke et 39 is secured to apanel 40 of'the instru ment. A red 41 securedto the said panel-andpassing through the upper endsof the U,- shapebrackets serves both tostrengthen the whole structureand to support (with insu-.

l'ating' sleeves 42 in between) the leafspring contactors or slidesl43and 44 of the respective windings. The seriesv connection ofv the; twowindingsis: established through the re spective plates 37,-each of'theseplates being electrically connected both to one endof the respectivewinding and (preferably through the; medium of a springwasher not shown)the respectivelbracket 38 or 39. "The other endof each winding isconnected to the respective plate 36 and thence,-through the springcontactor 45, to a terminal 46 mounted iii-insulated relationjupon thebracket 39.

What we claimand desire ters Patent is v l. A wireless receivingapparatuscomprise ing an'electrondischarg'e valveof the audion tosecurebyLete 3 type the filament of which is adapted to be energized by meansof alternating current, means for establishing the input circuit to thevalveat the filament end through an adjustable tapping point ofa'resistance connected in parallel to thevalve filament, and meanswhereby the said alternating current for en-' ergizing the valvefilament is supplied through. the medium of a transformer having primaryand secondary windings, at least one of said windings being divided intoa plurality of portions adapted to be connected in series or in parallelrelation selectively.

2. A wireless receiving apparatus comprising a plurality of electrondischarge valves of the audion type the filaments of which arerespectively adapted to be energized by means of alternating current,means for establishing the input circuits to the respective valves atthe filament ends through adjustable tapping points of resistancesconnected in parallel to the valve filaments, and means whereby'the saidalternating current for ener'gizing the valve filaments is suppliedthrough the medium of a transformer having primary, and secondarywindings, at least-one of said Wvindings being divided into a pluralityof -"choke-coihhaving7am ironic b reon which are. 7 IV wound twowind1ngs,. one:0f whichkis-zin the: grid lead dfithe'ct her ofnwhichi'Sa in;thel

ffilamen subst t iallyi-vzisxfand for the-Q rpcsecsp lfiedq w 7 A Awii'eles's rece ling appafatli's accord ing tcic1aim'2,whereinthe-pi-imary amisec I {eachdividedintctwoj'pcrtionsand have each:.an associated" switch having a-fixed part tivelyftov th'e-founndsofsaidtwcportions' V fandiar movable partawhich canriestwo bridg- 1 g membensand' is" adaptedt'qbemoved se I lcpiyely to aPDSifiion inwhichsaidbridging .conncctinglthe portions inypara'lleli relation on toalpcsition ifiwhic'hcne of the bridging connectingfltha portions inseries and the: -'0t11'er:bridgin'g'member isdeadp15:1Awirelcssareceivingapparatus accord ingto -claim;lkwherein the saidresistance; which is c cnnectedi" parallel to. the vvalve q filamentcomprises two: portions wound sepa ratelycnconcentricrdrums'andvconnecte din serieswith one: another, one cf. saidportions having, a variable tapping "contactorassociatedtherewith anldtheother porti'onhaving Variable contacto for'varyingthetqtal .re-

tance forgthepurpcsc spccified;d l v Ifiwitness whereof Weaflix oursignatures.

W ALFRED :I-IENRY MACKLLEY,

WILLIAM STEA NLEY- FLIGHT. 1

ondary'windingsof thesaidtransformr are j v y whichlcarnies fourcontacts connected respeca I v r 7 members bridge pai r spofSiaidcontacts for V

